The present invention generally relates to parking brakes and, more particularly, to an electrically powered parking brake.
Almost all vehicles have a parking brake mechanism, and most of these vehicles have a hand or foot activated lever for manually actuating the parking brake mechanism. Typically, these levers are attached to a cable that causes displacement of the cable and operation of the attached parking brake mechanism. There is a need to provide an electrically actuated cable mechanism that operates reliably with a minimum number of parts and has a low cost, so that manually actuated mechanism may be replaced or easily selectively replaced.
It is known in the art to provide electric-motor driven brake systems. For example, see U.S. Pat. Nos. 4,281,736, 4,561,527, 4,629,043, 4,795,002, 4,865,165, 5,180, 038, 5,485,764, 5,542,513, and 5,590,744 which each disclose an electric motor-driven brake system, the disclosures of which are expressly incorporated herein in their entirety by reference.
While these electrical-motor driven brake systems may adequately actuate the brake mechanisms with varying degrees of success, the electrical drive system occasionally fails and the brake system cannot be applied or released. Accordingly, there is a need in the art for an improved electric parking brake assembly with a manual override system which can selectively operate the brake system when desired. Preferably, the mechanism has over torque protection, is automatically disengaged when not in use, has a relative small package size, has a relatively small number of components, and is relatively light weight.
The present invention provides an electric parking brake for a motor vehicle which overcomes at least some of the above-noted problems of the related art. According to the present invention, a manual override mechanism for an electric brake comprises, in combination, a rotatable connector to be operably connected to the electric brake assembly, a flexible cable having an elongate outer conduit and an elongate inner core extending within the conduit, and a housing. The inner core has a first end and a second end. A core end fitting is secured to the first end of the inner core. The core end fitting is located within the housing and is longitudinally movable relative to the outer sheath between a first position wherein the second end of the inner core is in operable engagement with the connector to rotate the connector upon rotation of the core end fitting and a second position wherein the second end of the core is out of operable engagement with the connector such that rotation of the core end fitting does not rotate the connector A spring element biases the core end fitting into the second position. The spring biased core end fitting enables the manual override mechanism to be selectively operable by the operator of the motor vehicle.
According to another aspect of the present invention, a manual override mechanism for an electric brake comprises, in combination, a flexible cable having an elongate outer conduit and an elongate inner core extending within the conduit, a conduit end fitting secured to an end of the outer conduit, a housing located within the conduit end fitting and rotatable therein, and a core end fitting secured to a first end of the inner core. The core end fitting is located within the housing. A clutch is provided between the housing and the core end fitting such that rotation of the housing relative to the conduit end fitting causes rotation of the core end fitting when below a predetermined torque and rotation of the housing relative to the conduit end fitting does not cause rotation of the core end fitting when above the predetermined torque. A connector to be operably connected the electric brake assembly and engaged by the second end of the inner core is preferably provided. The clutch prevents damage to the brake assembly due to manual over torque.
According to yet another aspect of the present invention, a manual override mechanism for an electric brake comprises, in combination, a flexible cable having an elongate outer conduit and an elongate inner core extending within the conduit, a conduit end fitting secured to an end of the outer conduit, a housing located within the conduit end fitting and rotatable therein, a core end fitting secured to an end of the inner core. The core end fitting is located within the housing and is longitudinally movable from a first position to a second position such that the end of the inner core moves toward the end of the outer conduit. A clutch is provided between the housing and the core end fitting such that rotation of the housing relative to the conduit end fitting causes rotation of the core end fitting when below a predetermined torque and rotation of the housing relative to the conduit end fitting does not cause rotation of the core end fitting when above the predetermined torque.
From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of electric parking brakes. Particularly significant in this regard is the potential the invention affords for providing a high quality, reliable, light weight, small packaged, easily assembled and disassembled, low cost assembly having a manual override. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below.